Genetic disorders having cardiac effects are, typically, potentially lethal without proper therapy or medication, and therefore it is of essential importance to detect signs of such a disorder early on. Moreover, cardiac side effects are a one of the most common reason for withdrawal of a drug from the market, and therefore reliably capturing any potential cardiac side effects of a drug already during the development phase would be highly beneficial.
Cardiac safety analyses are typically carried out using animals as model organisms and/or ectopic expression of single ion channels in non-cardiac human cells. Human cardiomyocytes (CMs) have been very challenging to study, since primary CMs are hard to obtain as the myocardial biopsy is a high risk procedure and the CMs dedifferentiate fast and stop beating in cell culture conditions. Moreover, previously known techniques for measuring the functionality of the CMs are challenging and do not provide high or even medium throughput.
While cardiac effects can in principle be examined by analyzing the functionality of human CMs, known techniques for such analysis are typically time-consuming and also somewhat unreliable or even impractical to properly support diagnostic purposes, hence failing to provide an analysis of the functionality of CMs that would provide a satisfactory basis for wide-spread use for supporting diagnostic purposes. In this regard, e.g. “Brüggemann A., S. Stoelzle, M. George, J. C. Behrends, and N. Fertig, Microchip technology for automated and parallel patch-clamp recording, Small 2:840-846, 2006” discloses so-called patch clamp approach that may be used to analyze the functionality of a single CM. However this technique requires special, relatively expensive instrumentation, and laborious manual work requiring highly skilled personnel. For example “Braeken D., R. Huys, D. Jans, J. Loo, S. Severi, F. Vleugels, G. Borghs, G. Callewaert, and C. Bartic, Local electrical stimulation of single adherent cells using three-dimensional electrode arrays with small interelectrode distances. Conf. Proc. IEEE Eng, Med. Biol. Soc. 2756-2759, 2009” and “Pekkanen-Mattila M., E. Kerkelä, J. M. A. Tanskanen, M. Pietilä, M. Pelto-Huikko, J. Hyttinen, H. Skottman, R. Suuronen, and K. Aalto-Setälä, Substantial variation in the cardiac differentiation of human embryonic stem cell lines derived and propagated under the same conditions—a comparison of multiple cell lines, Ann. Med. 41:360-370, 2009” disclose a technique based on microelectrode arrays (MAE) that provide a platform for analyzing larger aggregates of CMs with less manual work than required in the patch clamp technique, but due to dimensions of the electrodes and distances between electrodes, they are not suited for studying a single CM. As further example of related art, “Novakova M., J. Bardonova, I. Provaznik, E. Taborska, H. Bochorakova, H. Paulova, and D. Horky, Effects of voltage sensitive dye di-4-ANEPPS on guinea pig and rabbit myocardium, Gen. Physiol, Biophys. 27:45-54, 2008” discloses a technique based on voltage sensitive dyes such as e.g. di-8-ANNEPS that provides a solution to analyze a single CM. However, this technique is based on fluorescence imaging and the dyes interact with some ion channels e.g. hERG, thus potentially altering the electrophysiological properties of the CMs.